I really like playing Kart-Hadast because of the range of troops they have that you mentioned above as well as the range of enemies you can fight. You have the Numidian rebels, Egyptian-Greeks, Romani, Lusos, and Gauls just a few clicks away. There's also a range of fun ways to fight that role-play well with the faction, such as launching a massive naval raid or invasion to capture the heartland of a faction, or do what they did historically and take the mines in Iberia. There was also a guide somewhere that gave a comprehensive pros vs. cons report regarding where you can expand.
The way I always play is take all the African rebel territories (because I hate the blank spots on the map :P) then I take Africa and buy off the Ptoly troops at the same time. Then I either take Sicily or go after the Egyptians. It's actually a fun campaign and you don't really miss the peltasts since there are other troops that can take their place.